#include "uclisp.h"
#include "internal.h"
#include "utility.h"

#include <stddef.h>
#include <stdbool.h>
#include <string.h>

struct ucl_object *ucl_car(struct ucl_object *list) {
    UCL_COND_OR_RET_ERROR(
        list != NULL && list->type == UCL_TYPE_CELL,
        "Invalid type of argument 0 to 'ucl_car'");

    struct ucl_object *car = list->cell.car;
    if (car == NULL) {
        return ucl_nil_create();
    }

    return car;
}

struct ucl_object *ucl_cdr(struct ucl_object *list) {
    UCL_COND_OR_RET_ERROR(
        list != NULL && list->type == UCL_TYPE_CELL,
        "Invalid type of argument 0 to 'ucl_cdr'");

    struct ucl_object *cdr = list->cell.cdr;
    if (cdr == NULL) {
        return ucl_nil_create();
    }

    return cdr;
}

struct ucl_object *ucl_nil_create() {
    return ucl_cell_create(NULL, NULL);
}

struct ucl_object *ucl_t_create() {
    return ucl_symbol_create(strdup("t"));
}

struct ucl_object *ucl_predicate(bool value) {
    if (value) {
        return ucl_t_create();
    } else {
        return ucl_nil_create();
    }
}

struct ucl_object *ucl_list_length(struct ucl_object *list) {
    UCL_COND_OR_RET_ERROR(
        list != NULL && list->type == UCL_TYPE_CELL,
        "Invalid type of argument 0 to 'ucl_list_length'");

    struct ucl_object *node = list;
    if (list->cell.car == NULL) {
        return ucl_int_create(0);
    }

    int length = 1;
    while (node->cell.cdr != NULL) {
        node = node->cell.cdr;
        length++;
    }

    return ucl_int_create(length);
}

struct ucl_object *ucl_list_nth(struct ucl_object *list, int n) {
    UCL_COND_OR_RET_ERROR(
        list != NULL && list->type == UCL_TYPE_CELL,
        "Invalid type of argument 0 to 'ucl_list_'");

    int length = ucl_list_length(list)->integer;
    UCL_COND_OR_RET_ERROR(length > n, "Position n >= list length in ucl_list_nth");

    struct ucl_object *node = list;
    for (int i = 0; i < n; i++) {
        node = node->cell.cdr;
    }

    return node->cell.car;
}

struct ucl_object *ucl_truthy(struct ucl_object *obj) {
    // TODO: Implement me
    return ucl_error_create("Unimplemented function 'ucl_truthy'");
}

struct ucl_object *ucl_tuple_create(struct ucl_object *obj0, struct ucl_object *obj1) {
    struct ucl_object *tuple = ucl_cell_create(obj0, NULL);
    ucl_list_append(tuple, obj1);
    return tuple;
}

struct ucl_object *ucl_list_append(struct ucl_object *list, struct ucl_object *obj) {
    struct ucl_object *iter = list;

    if (list->cell.car == NULL) {
        list->cell.car = obj;
        return list;
    }

    while (iter->cell.cdr != NULL) {
        iter = iter->cell.cdr;
    }
    iter->cell.cdr = ucl_cell_create(obj, NULL);

    return list;
}